Detection of Colorado Tick Fever viral RNA in acute human serum samples by a quantitative real-time RT-PCR assay

A quantitative real-time RT-PCR assay for the detection of Colorado Tick Fever (CTF) viral RNA in human clinical samples is presented. The sensitivity of this assay has been shown to be greater than that of the isolation of virus in Vero cells by standard plaque assay in a direct comparison. The specificity of the CTF quantitative real-time RT-PCR assay was determined by the exclusive detection of CTF viral RNAs when applied to a diverse panel of CTF viral isolates and reference strain agents known to circulate in areas of CTF virus transmission. Lastly, the quantitative real-time RT-PCR assay demonstrated exceptional sensitivity for the detection of CTF viral RNA in acute human serum. The quantitative real-time RT-PCR assay is efficient, sensitive and specific and as such is useful for the detection of CTF viral RNA in the diagnostic or research laboratory.

Hematologic manifestations of viral infections

Many infections have an impact on the hematologic system. There also are many noninfectious processes associated with abnormalities of the blood and iatrogenic causes such as pharmacologic therapy that also may affect the marrow or circulating cellular elements. Viral disease may impact on one or more components of blood, and familiarity with these associations can assist in anticipating the course of disease and reducing the need to seek out other etiologies for the usually transient hematologic abnormalities that often occur in patients with viral infections.

Colorado tick fever in a resident of New York City

When a traveler returns from abroad with a febrile illness, clinicians appropriately concern themselves with a potentially vast array of diagnostic exotica. The patient we describe herein did not leave the United States but nevertheless posed the same clinical dilemma after returning home to New York City from the western United States. This case of Colorado tick fever, acquired on the Utah-Colorado border and first expressed in Manhattan, serves as a useful reminder of the importance of taking a careful travel history for national as well as international travelers.

Virus-induced leukopenia: Colorado tick fever as a human model

Eight patients with Colorado tick fever were studied to determine whether alterations in the production of granulopoietic stimulatory or inhibitory factors (or both) could be found in association with the leukopenic state of the disease. The studies demonstrate that in the patients with Colorado tick fever the mononuclear cell production of colony-stimulating factor is decreased and that there is an increase in circulating inhibitory factors in the serum of such patients. The depressed mononuclear cell colony-stimulating activity does not appear to be reversible by addition of either endotoxin or normal human serum. Characterization of these serum inhibitory factors may facilitate understanding of leukopenia in human disease.